Hip-hop and guide numbers

August 1, 2011 by Bruce · Leave a Comment

A couple of weeks ago, Ama Garatshun (the female model at our Noir Deux shoot) posted on Facebook that some friends of hers were looking for a photographer to do a shoot for the album cover for their hip-hop outfit, Live For Music.
I responded that I would be interested.
The guys checked out some of my prior work and were happy with what they saw.
They didn’t really have a particular theme in mind and left it to me to throw some ideas out there.
Given that they were planning on including Ama in the shoot (despite her not being a part of the musical group), I suggested that we have Ama dressed up to the nines in a full length cocktail dress, elbow-length gloves, go the real “socialite” look, have the boys all looking typically “street” and shoot in a run-down, burnt out, half demolished house. The idea being to play up the contrasts.
The guys liked the idea.
For a while, we were going to shoot in a house that matched that description. But then a week before the shoot, the guy I was liasing with said they were interested in doing the shoot in the old Dunlop-Slazenger factory at Alexandria in Syndey’s southern suburbs.
This factory was where Dunlop-Slazenger manufactured all their tennis and squash raquets, their running shoes and so forth. I don’t know exactly when it was closed down, but if I had to guess, I’d say it’s been at least 20 years since Dunlop-Slazenger closed up shop and moved on.
These days, it’s become quite the ‘artspace’. Every day, you can see film crews and photographers going in there to shoot all manner of things, kids are in there tagging the walls 24/7, and the place has developed a very rough, heavily layered look.
So, yesterday, we went down there to do the shots for the album cover.
Over a 3 hour period, we did some solo portraits of each of the band members, plus a variety of full band shots both with and without Ama.
The only sour note to the day was when, whilst moving a light stand from one location to another, the speedlight and Flashwave 3 receiver decided to depart the clamp and stage dive the concrete from 6 foot above ground. Ouch.
Thankfully, the Flashwave 3 receiver survived unharmed.
The speedlight however, was not so lucky. Now, the photographer reading this is probably thinking “Aren’t your speedlights more expensive than a Flashwave 3 receiver”?
Actually, no!
The beauty of using cheap Chinese knock-off speedlights (yours for the princely sum of AU$45 each from Ebay!) is that if something like this happens, it’s not the end of the world.
If this had been my $600 Sony flash, I’d have been pretty cut up about it.
So, now you’re thinking “But do your cheap Chinese knock-off speedlights do TTL?”
No, they don’t, but who cares?
Having been taught how to calculate the flash power based on the combination of the aperture and the guide number of the speedlight, I do everything manually anyway, so the absense of TTL metering is not an issue for me.
As Shelton has mentioned many times on Shutters Inc, learning how to calculate your flash requirements manually is an important talent for any photographer to have in their mental toolbox.
For those who haven’t heard the podcast, or didn’t understand the verbal delivery of the formula, allow me to recap it here.
The guide number of your speedlight (or studio flash head, if you like!) tells you how many meters the flash will throw light at 100iso at an aperture of f1.
Now, few of us have lenses that open to f1. Which is probably a good thing! You wouldn’t get much depth of field at f1!
So, let’s assume that you have a speedlight with a guide number of 40.
At an aperture of f1 @ 100iso, and at full power, this flash will correctly expose an object that is 40 metres away from the flash! That seems like a lot of power… until we decide to work with more realistic apertures!
Let’s suppose we are shooting at f8.
What is our flash doing now?
Well, that’s where the magic formula comes in.
Guide number divided by aperture equals distance.
Or… guide number divided by distance gives us aperture.
So, if we want to shoot at f8, we divide 40 by 8 and come up with 5.
This means that with our speedlight at full power, and shooting at f8, our speedlight should be 5 metres from our subject.
If you want your subject closer to the speedlight than that, then you either reduce the power of the flash by one stop (which will halve our flash-to-subject distance) or close your aperture down one stop (to f11).
I know this sounds like a really challenging thing to get your head around, but believe me, if you were to spend just ONE DAY practising this, you would have it nailed!
And you would never have to guess at where to set your flash’s power level ever again.
You’d do some quick math in your head, you’d dial in the power level and you’d be pretty much on the money right from the first shot.
To summarise that formula, just remember this: